Without limiting the scope of the invention, its background is described in connection with liquid sustained release suspensions.
One such method of making sustained release particles is taught in U.S. Pat. No. 6,120,787, issued to Gustafsson, et al., which teach a method of preparing parenterally administrable sustained release microparticles, that include preparing core particles in an aqueous medium that is essentially free from organic solvent, a biologically active substance being entrapped therein during or after said preparation, drying the core particles and coating the same with a release-controlling polymer by air suspension technique so as to create a shell on the core particles without any detrimental exposure of the active substance to organic solvent.
Another sustained-release composition includes an amorphous polymer are taught in U.S. Pat. No. 6,613,358, issued to Randolph, et al., which provided for a sustained release composition for sustained release of a pharmaceutical substance that includes a biocompatible polymer that is highly amorphous and a pharmaceutical substance in a hydrophobic ion complex with an amphiphilic material. A compressed antisolvent method for manufacturing the composition it taught as are various product forms incorporating the composition and various uses for the composition.
Yet another sustained release drug formulation is taught in U.S. Pat. No. 5,980,945, issued to Ruiz in which a sustained release drug formulation includes a drug; a biodegradable polymer that is insoluble in water; and an oil vehicle in which both the drug and the polymer are dissolved. The oil vehicle contains 10-100% by volume of a pharmaceutically acceptable oil and 0-90% by volume a pharmaceutically acceptable liquid carrier for the drug or the polymer.
Despite these advances the release of the drug from the ion resin system is modified by coating the resin conjugates. There are several products on the market in both the solid form and as a liquid suspension that use this technology. This new invention describes a simple but very effective technique that can be used to alter the drug release from the ion resin system using the addition of suitable salts. It also describes the impact of salt addition, in the suspension formulations of drug resin conjugates, on the drug release profiles. This technique can be used to modify and manipulate the drug release profiles from the ion resin system.